Spiral punch.



`H. C'. ROBERTS.

, 1908. 921,463. l Patented May 11, 1909.

HARRY C. ROBERTS, OF MAXTON, NORTH CAROLINA.

SPRAL PUNCI.

No. saines.

Application filed July 2B, 1908.

S ecicaton o Letters Patent Patented May 1l, 1909.

Serial No. 445,762.

To all whom if: may concern.'

Be it 1Known that l, HARRY C. ROBERTS, a citizen ofthe United States,residing at Maxton, in the county of Robeson and State of NorthCarolina, have invented certain new and useful improvements in SpiralPunches; and l do hereby declare the following to be a full, clear, andexact description ofthe invention, suc-h as will enable lothers skilledin the art to which it appertains to malre and use the same, referencebeing had to the accompanying drawings, and to the letters of referenceinarlred thereon, which form a part of this speciiication.

This invention relates to new and useful improvements in spiral punchesespecially adapted for making holes in belting for lacing the ends ofbelts together and the obiect of the invention is to produce a simpleand eifrcient device of tais nature so constructed as to cut the holewithout expanding and loosening the layers of which the usual belts areconstructed and which is found to be a trouble where the apertures aremade by the ordinary tapering punch. In belts which are commonly usedand which are made up of layers, rubber and fabric, the formation of theholes by means of a solid unyielding punch, the layers which arefastened together are loosened from one another and which weakens thebelt when laced together through apertures made by the ordinary punch.

More specifically, the present invention consists of spiral punch soarranged that, when it is turned either by hand or otherwise against thebelt orother article to be punched, the cutting end of the tool willcontract slightly by reason of a cutting lip projecting from the end ofthe device, thus causing a core to be cut of slightly smaller diameterthan the normal expanded diameter of the punch and which will avoid thecore adhering to the walls of the punch after the latter is withdrawnfrom the article in which the hole has been formed.

rl`he invention comprises various details of construction, combinationsand arrangements of parts which will be hereinafter fully described andthen specifically defined in the appended claims.

l illustrate my invention in the accompanying drawings, in which Figure1 is a side elevation of my improved spiral punch. Fig. 2 is a crosssectional view through the cutting end of the punch and also a coreshowing the punch in its contracted forni while cutting the core. Fig. 3is a similar view showing the core already cut and the punch removedfrom the belt or sheet in which the hole is made' and showing thecutting end expanded to its normal positien with a slight spaceintervening between the circumference of the core and the end surface ofthe punch. Fig. 4 is an enlarged detail view of the cutting end of thepunch showing the cutting lip thereon, and Fig. 5 is a verticalsectional view through the punch.

Reference now being had to the details of the drawings by letter', Adesignates a spiral punch which is hollow and slightly taperinglongitudinally, as shown in the longitudinal sectional view. ln thedrawings said punch is shown as having a solid shank port-ion B with anend designed to i'it the socket of a bit stock. The cuttingvend of thepunch, which is shown in the sectional view as tapering to a sharp edge,is provided with a cutting lip D which, when the punch is turned totheright, is adapted to cut into the sheet in which the hole is to beformed and, as the cutting lip engages the material and while the punchis being rotated, the thin tapering cutting end of the punch will have atendency to contract thus cutting a core which is of a diameter slightlyless than the diameter of the cutting end when the tool is expanded fromits normal position, as shown in detail Figs. 2 and 3 of the drawings.

in operation, when the end of the punch is placed against the sheet ofmaterial through which the hole is to be formed and pressure applied tothe tool as the latter is rotated to the right, said lip will outlineland cut a cylindrical core and, as the cutting end is slightly resilientand when the cutting lip engages the material to be cut, it will have atendency to contr ct the cutting end of the punch and, after the corehas been cut and the punch removed from the sheet of material from whichthe core is cut, he free end of the tool will expand slightly as shownin Fig. 3, thus preventing the core being wedged in the punch as iscommonly the trouble -with the usual form of punch in which no provision is made for the expansion of the same as l in the present instance.As the hollow portion of the punch increases in diameter toward thestock or Shank portion, the cores as they are successively cut willreadily fall out through the spiral portions of the tool as will bereadily understood.

v Thet I claim to be neT is:-

A hollow spiriti punch of a resilient metal, the end of which terminatesin e circular outlined cutting` edge at right angles to the 5 length ofthe punch and extending into the opposite edges of the spiral part of'the punch and provided with e conVeXed lip projecting Witnessesz fromsaid cutting` edge adjacent to the spiral ROBERT A. BosWELL, edge of thepunch and merging into the edge l A. L. HOUGH.

of the spiral portion of the punch as set 10 forth.

ln testimony whereof I hereunto affix my signature in the presence oftWo Witnesses.

I t i l HARRY c. ROBERTS.

